Gr. R. VINE ON THE FAMILY DIAST0P0PJD.33. 



385 



a careful study of the crustaceous forms from several horizons, 

 ranging from the Pea-Grit to the Coral Rag, I can detect at least 

 three types that have not been specially noticed, so far as I am 

 aware, by previous authors. They may, and I have not the least 

 doubt that they have been, casually identified ; but that is all. 

 They deserve, however, more than a passing notice, because some of 

 these types, when they pass into the Bradford Clay and the Forest 

 Marble, delicately preserved on branches of Terebellaria and frag- 

 ments of broken shell, assume an altogether different character. 

 Some of them are beautifully papyraceous ; others appear to have a 

 kind of basal lamina extending slightly beyond their circumference, 

 a character I have never observed in the Inferior-Oolite species. 



The papyraceous species of the Lower Oolite are also deserving 

 of closer study than I can possibly give to them. Such work belongs 

 rather to local students than to me. They, too, may study the 

 types as they pass from one stratum to another ; and in so doing, I 

 would recommend them to mark the beginnings of the divergences, 

 and the boundary lines of each of the four types given ; and by 

 doing so they will aid the paleontologist in classifying the evolu- 

 tionary stages of a most important genus. 



2. Diastopoea ventricosa, mihi. Plate XIX. figs. 15-17. 



Zoarium adnate, discoid in the earlier stages of growth, of most 

 irregular outline in its later stages. Zooscia produced and partially 

 free in the centre, gradually depressed towards the margin ; tubes 

 slightly bent and swelling towards the orifice, which causes a con- 

 striction of the circular or subcircular mouth ; cells well separated, 

 the proximal ends being immersed in the zoarium. Ocecia very 

 largely developed, sometimes round the margin, at other times indis- 

 criminately all over the colony, involving two or three cells or only 

 a considerable swelling of a single tube. In the best-preserved spe- 

 cimens the cells and also portions of the ooecia are finely punctate. 



Bab. On a weathered and partially smoothed pebble (No. 5), 

 Inferior Oolite, Pea-Grit, Cheltenham : Mr. Longe's Cabinet. On 

 drift wood, Chipping Norton, lowest beds, Great Oolite : Mr. 

 Watford's cabinet. Good specimens also in Museum of Practical 

 Geology, Jermyn Street. 



This species, or type, is a very peculiar one, well deserving especial 

 study. I have it from several localities, ranging from the Pea-Grit 

 to the Great Oolite. The specimen in Mr. Walford's cabinet 

 contains innumerable colonies piled up very irregularly round a 

 piece of water-logged coniferous wood of Oolitic age. The wood 

 was originally large ; but the broken fragment submitted to me for 

 examination was about three inches long, and from half to three 

 quarters of an inch in diameter. The incrustation of the wood, 

 made up wholly of colonies of Diastopora, varies in thickness from 

 a quarter to half an inch, the margins of the newer colonies 

 gradually becoming compressed into the general mass through 

 successive stages of growth. The ventricose swellings are not so 

 typical in this specimen as in the more beautiful specimens from 



